What is the fertile crescent and how is it related to Mesopotamia?

The fertile Crescent is a boomerang-shaped territory from the eastern Mediterranean to the Persian Gulf. The best farmlands were between the Tigris and the Eufrates Rivers, people settled down there and started to build an irrigation system so that they could use the annual floodings and the fertile silt that the rivers left behind. This territory was called Mesopotamia - between rivers - by the Greeks.